fix old dygraph a vlog bug (#47115)

paddle/fluid/imperative/dygraph_grad_maker.h

@@ -269,8 +269,8 @@ class TracedGradOp {
         return;
       } else {
         for (auto& var : vars) {
-          VLOG(6) << "SetOutput var name: " << var->Name();
           if (var && !var->OverridedStopGradient() && var->GradNode()) {
+            VLOG(6) << "SetOutput var name: " << var->Name();
             if (map_dirty_grad_node_.find(var) != map_dirty_grad_node_.end()) {
               // Because inplace var isn't a leaf var, it should have
               // dirty_grad_node.
@@ -283,8 +283,6 @@ class TracedGradOp {
               // the var with `stop_gradient=True` to the var with
               // `stop_gradient=False`.
               node_->InsertGradPendingNode(var->GradNode());
-              VLOG(6) << (*node_.get())[0].Type() << " insertGradPendingNode "
-                      << (*(var->GradNode().get()))[0].Type();
             }
           }
         }